Divide. Write your answer in simplest form. $ -\dfrac{5}{2} \div \dfrac{5}{7} = {?} $
Solution: Dividing by a fraction is the same as multiplying by the reciprocal of the fraction. The reciprocal of $\dfrac{5}{7}$ is $\dfrac{7}{5}$. Therefore: $ -\dfrac{5}{2} \div \dfrac{5}{7} = -\dfrac{5}{2} \times \dfrac{7}{5} $ $ \phantom{-\dfrac{5}{2} \div \dfrac{5}{7}} = \dfrac{-5 \times 7}{2 \times 5} $ $ \phantom{-\dfrac{5}{2} \div \dfrac{5}{7}} = -\dfrac{35}{10} $ Simplify: $ -\dfrac{7}{2}$